Snake Basin reservoir levels near average entering winter

Snake River Basin reservoirs are at normal levels despite a dry start to the snow-accumulation year, Idaho Power Co. reported.

Winter snowpack and the amount of water stored in the Snake system’s reservoirs largely determine how much water will be available for hydroelectric power generation, irrigation and other uses through 2019.

The 2016-17 winter left reservoirs flush with water that carried over to the summer of 2018. A warm, dry summer that increased irrigation demand, and a dry fall, dropped reservoirs to more typical levels, the Boise-based utility said.

Southwest Idaho’s Boise and Payette reservoir systems, which flow into the Snake, are near their average levels for this time of year, while the Upper Snake system in southeast Idaho and part of Wyoming is slightly above average, the company said.

“We are doing OK in terms of storage,” Idaho Power spokesman Brad Bowlin said. “We just don’t have the abundance of water we’ve had in the past two years.”

Water stored in reservoirs in the Boise River system was 104 percent of its long-term average compared to 143 percent a year ago, he said. Storage in the Upper Snake system was 120 percent of average, down from 183 percent. Water stored in Payette River system reservoirs stood at 97 percent, down from 118 percent.

Snowpack “has been minimal up to this point, and it’s still early,” Bowlin said. Currently unknown is “how much of the storage water will be needed to compensate for a light snowpack versus how much we can hold onto because we get a good snowpack. It just remains to be seen.”

“We will see what these (storm) systems coming through this weekend will provide, he said Friday, Nov. 23. “We anticipate snowpack out of these systems. This is typically the time we start to see some of the snow start to accumulate up in the high country.”